This invention pertains to air cooling and dehumidifying systems in general, and in particular to a unitary air cooling package utilized in off the road vehicles. Recent developments in earth moving vehicles have resulted in units often having a main propulsion engines above 1000 horsepower. The type of vehicles utilizing these high horsepower drives are very large and in most cases used in environments which are quite hostile to the operator of the vehicle. Consequently, it has become almost mandatory to provide an air cooling system which provides filtered cooled and dehumidified air in order to reduce operator fatigue and to allow improved concentration necessary to operate a vehicle of this size.
Operating cab location remote from the main prime mover presents a substantial problem in providing sufficient energy for operation of the cooling unit since belts or shafts conventional in automotive applications cannot be used. Electrical drives while flexible, incur substantial inefficiencies due to losses in generation and drive motors. Reliability of electric drives is also a problem when employed auxiliary systems on a hydraulic drive vehicle. Therefore, a cooling system eliminating an additional sub-system substantially increases overall vehicle reliability.
It has been found efficient and convenient to utilize available high pressure hydraulic fluid powered by the vehicles prime mover as an energy source. Therefore, it is necessary to operate all auxiliary components from hydraulic power. As stated earlier, the size and design of the vehicles involved requires that any cooling equipment be self contained except for its energy source and mounted directly over the heads of the vehicle operators. Earlier units have utilized electric motors to drive refrigeration compressors and fans needed for cooling, and in particular the compressors involved have in many cases become optimized for electric motor drive. Therefore, when operating this kind of equipment from a hydraulic motor, difficulties have been encountered due to output torque limits, low inertial mass of the hydraulic drive motors, and pulsating pressure in the source of hydraulic power.
Use of hydraulic energy for operation of all components of the air conditioner, as disclosed, provides additional reliability in the case of electrical system failure, allowing continuing or emergency operation of a diesel powered vehicle after loss of an electrical subsystem.